@article{EJDE_2011__2011__a66,
     author = {Zhao,  Kaihong and Li,  Yongkun},
     title = {Multiple positive periodic solutions to a non-autonomous {Lotka-Volterra} predator-prey system with harvesting terms},
     journal = {Electronic journal of differential equations},
     year = {2011},
     volume = {2011},
     zbl = {1216.34046},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2011__2011__a66/}
}